spirit-flash

Your mission

Compact a flash directory, keeping only the entries young enough to matter.

today's brief

January 21, 2004. Spirit had been on Mars 18 sols when it went quiet, then came back sending beeps and nothing else. Its flash still held every file written during the seven month cruise, and rebuilding that directory in RAM took more memory than the rover had, so it rebooted. Then it did it again, about once an hour, for days. JPL talked it into a mode that ignored the flash and cleared the old files out. Do the sweep.

See it in action

compact(out, {5,900,40,1200}, 4, 100)

Expected result

2 5 40

Your checklist

For your own tracking. Tests grade your code.

age holds n entry ages in sols, in the order they sit on the flash.
Copy into out, in the same order, every entry whose age is at most keep.
An entry older than keep is dropped, and nothing is written for it.
Return how many entries were copied.

More examples

compact(out, {900,800}, 2, 100)

Expected result

compact(out, {1,2,3}, 3, 100)

Expected result

3 1 2 3

Constraints

Expected files

flash.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions

spirit-flash

Your mission

Compact a flash directory, keeping only the entries young enough to matter.

today's brief

See it in action

compact(out, {5,900,40,1200}, 4, 100)

Expected result

2 5 40

Your checklist

For your own tracking. Tests grade your code.

age holds n entry ages in sols, in the order they sit on the flash.
Copy into out, in the same order, every entry whose age is at most keep.
An entry older than keep is dropped, and nothing is written for it.
Return how many entries were copied.

More examples

compact(out, {900,800}, 2, 100)

Expected result

compact(out, {1,2,3}, 3, 100)

Expected result

3 1 2 3

Constraints

Expected files

flash.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions